PMDX-131 reactivation ? what am I overlooking?

[knuut]

When I apply power (48V DC) to J1 the motors lock. I have a Jumper installed from 'E-stop' to ground on J10 (and the motors de-coupled from the mill so they can free-wheel without moving anything) and the appropriate curent limiting resistors in the green terminals above each Gecko.
   When I use the 'Stepper Configuration Wizard' in LinuxCNC to asign the pins 2 through 10 according to the chart on page 16 of the PMDX-131 manual and run the axis test routine, nothing happens and the motors remain locked. Tried unassigning pin 10, no change. Tried moving and then removing the jumper  on JP1, still no change. I am out of ideas so any suggestions would be helpful.

[Steve Stallings]

Two things come to mind.....

First, it is easy to get the Step and Direction signals swapped. Double check
that you have Step on pin 3 and Direction on pin 2.

Second, the PMDX-131 is an older board that was designed back when all
Gecko drivers required +5 as the Com signal, and this cannot be changed
easily on the PMDX-131. Unfortunately the popular G203V drivers REQUIRE
ground as common. If you have G203V drivers, you have a problem.

[knuut]

Definitely 201s (not 201-Xes or 203s) purchased around 1999 or 2000 ... used for about a week back then and not used since.
I tried setting the pin configs both ways (step on 3, dir. on 2 and step on 2, dir on 3) with the same results; repeatedly running the test program would occasionally get me a single step but nothing like a normal stepper run. I also tried reversing two of the motor leads with no change.

[Steve Stallings]

Is the "Outputs Enabled" LED at the right hand end of the board illuminated? If not
no steps will be going out.

Do you have JP1 set in the CP-OK position? If so you must have Mach configured to
supply a "Charge Pump" on pin 17.

Do the on screen DRO's follow your move commands. If the DRO's do not move,
then Mach is not sending out pulses.

[knuut]

The LED is on and JP1 is set to 'E-stop'. The test routine in the LinuxCNC 'Setup Wizard' doesn't show DRO's so I used the MDI mode in regular LinuxCNC run screen. The DRO's move and so do the steppers, at least a bit. A 'G1 X1 F10' command generates a 1" move on the DRO but the stepper only goes a quarter turn which would be about .050 inch if it were actually connected to the 5 turn/inch lead screws. It's like 95% of the step commands are being lost.

[knuut]

I found the  LinuxCNC setting for microstepping, turned it to maximum (10), and everything smoothed out and started moving more or less normally. It appears I have been dealing with the LinuxCNC learning curve and not a PMDX problem. Thanks for the help.

[Steve Stallings]

Thanks for letting us know about your progress.